1. Field of the Invention
The invention relates in general to an axle structure, and more particularly to an axle positioning structure employed in lightweight devices.
2. Description of the Related Art
Digital cameras offer considerable advantages over conventional film-type cameras in that the digital image data may be stored, processed, and/or reproduced with ease. The relative ease of handling and processing the digital image data produced by digital cameras allows users to readily look and examine the outcome of digital images.
With the advanced development of 3 C (consuming electronics product, computer and communication) industries, the current manufactures tend to install a built-in digital camera in various portable devices such as notebook computers, mobile phones, personal digital assistants (PDAs), and so on. Take the portable device with a flip cover device (hereinafter referred to as a clam-shaped device) as the example, a built-in digital camera is mainly installed in the rotating axle pivotally connecting the cover and the main body of the clam-shaped device, or otherwise the built-in digital camera is installed in the forward part of the cover. FIGS. 1A to 1C are lateral views showing a clam-shaped device equipped with a built-in digital camera. The clam-shaped device includes a cover 110, a main body 120 and a rotating -axle 130. The rotating axle 130 connects the cover 110 and the main body 120, so that the cover 110 can pivotally rotate relative to the main body 120 to allow the clam-shaped device to be opened or closed. A digital camera 100 is rotatably coupled to the forward part of the cover 110 through an axle 104 so that the lens 102 of the digital camera 100 can change the angle of view to enlarge the field of vision by rotating the axle 104.
In the beginning, before the digital camera 100 rotates with respect to the cover 110, the rotating angle is zero degree, as shown in FIG. 1A. FIG. 1B appears the digital camera 100 rotating 90 degrees with respect to the cover 110. The digital camera 100 rotates the ultimate rotating angle is 180 degree with respect to the cover 110, as shown in FIG. 1C. Users can rotate the lens 102 of the digital camera 100 with adjustable 0–180 degrees by rotating the axle 104 to capture the shot.
Conventionally, in order to allow the axle 104 to have a positioning function, a small-scale hinge mechanism is employed so that the digital camera 100 can be fixed after rotating a determined angle between 0–180 degrees. However, it is not necessary to use the small-scale hinge mechanism here due to the light weight of the digital camera 100 so that the torsion required for the digital camera 100 is less than that the small-scale hinge mechanism offers. Besides, the outer diameter of the axle 104 can be allowed within 4 mm. Moreover, considering the higher production cost and the lower manufacture yield rate, it is not applicable when the hinge mechanism is employed in being the axle 104 of a clam-shaped device such as the digital camera 100.
FIG. 2 is a cross-sectional view showing the structure of a conventional axle. The axle 104 includes a sleeve 200 and a shaft 210; the shaft 210 is rotatably coupled to the sleeve 200. The bottom 202 and the inner wall 204 of the sleeve 200 form a receiving space 206, and the bottom 202 of the sleeve 200 has a hole 208. The first end of the shaft 210 goes through the hole 208 and then is fixed to the digital camera 100. The second end of the shaft 210 is disposed within the receiving space 206 of the sleeve 200. Besides, the shaft 210 has a stopper 212 protruding from the second end of the shaft 210 for stopping the shaft 210 from axially moving so as to prevent the shaft 210 from slipping out of the receiving space 206 through the hole 208.
In FIG. 2, the shaft 210 can be positioned by a design analogous to wedging the shaft 210 into the sleeve 200. However, the coupling portion of the shaft 210 and the sleeve 200 is suffered a lot of wear and tear after repeatedly rotating. The analogous wedging design consequently becomes loosening so that the digital camera 100 cannot be positioned at a determined angle to meet users' needs.